Recently, such tape recorders which can handle both the analog compact cassette tapes (hereinafter, referred to simply as C-cassettes) and digital compact cassette tapes (hereinafter, referred to simply as D-cassettes) have come to be known in the art. In the C-cassettes, information is recorded and reproduced using an analog signal, while in the D-cassettes, information is recorded and reproduced using a digital signal.
The shapes of the C-cassettes and D-cassettes used in such tape recorders are described as follows.
As illustrated in explanatory drawings, FIGS. 2(a) and (b), a C-cassette 1 is composed of a cassette-half of A-side (hereinafter, referred to as "A-side 2"), a cassette-half of B-side (hereinafter, referred to as "B-side 3"), and a magnetic tape, not shown.
On the A-side 2, a machine-screw hole 6 is provided in the center of a raised portion 10, which will be described later. Through the machine-screw hole 6, a machine screw 7 puts together the A-side 2 and the B-side 3. As illustrated in FIG. 3, the machine screw does not penetrate through the surface of the B-side 3. Further, as illustrated in FIGS. 4 (a) and (b), the C-cassette 1 is provided on both sides with raised portions 10 and 11, each of which is formed with a trapezoid-like shape as seen from its cross section. Here, both of the A-side 2 and the B-side 3 of the C-cassette 1 are made of a non-conductive resin.
The C-cassette 1 contains a magnetic tape 8 which has two upper and lower tracks formed thereon. When the C-cassette 1 is loaded in a tape recorder with the A-side 2 seen by the user, recording and reproducing are executed on and from the lower track in the forward mode. On the other hand, in the reverse mode recording and reproducing are executed on and from the upper track.
Conversely, as illustrated in FIGS. 6(a) and (b), a D-cassette 15 is provided with a cassette shell 12 made of a non-conductive material. On a surface 16 of the cassette shell 12, a paper label 17 is adhered so that it covers most of the surface thereof. This D-cassette 15 is normally loaded in a tape recorder with the label 17 side up as seen by the user; therefore, in most cases, the D-cassette 15 does not have the definition of A-side and B-side. If the D-cassette 15 is loaded with the label down as seen by the user, it is misloaded.
Further, the D-cassette 15 differs from the C-cassette 1 in that it is provided with a slider 18 made of a metallic material, which reciprocally moves and slides in the directions indicated by arrows C-D at the front portion of the D-cassette 15. As illustrated in FIGS. 7(a) and (b), the slider 18 is constituted of an upper bent portion 18a, a slider front portion 18b and a lower bent portion 18c, virtually forming a U-shape. The depth dimension L2 of the upper bent portion 18a is shorter than the depth dimension L3 of the lower bent portion 18c. Here, in the cassette shell 12 of the D-cassette 15, there is no machine-screw hole and no machine-screw is used.
The D-cassette 15 contains a magnetic tape 8 which has two upper and lower tracks as in the C-cassette 1; yet, the track closer to the surface 16 is used in the forward mode and the other track further therefrom is used in the reverse mode, which makes it different from the C-cassette 1. Therefore, in the case of the D-cassette 15, unless the user improperly loads the cassette, recording and reproducing are executed on and from the track in the forward mode when the user specifies the forward mode, and are executed on and from the track in the reverse mode when the user specifies the reverse mode.
In such magnetic tape apparatuses, in the case of recording or reproducing the C-cassette 1 in the automatic reversing mode, if it is loaded in the apparatus with the A-side 2 up, recording or reproducing is executed on or from the predetermined track in the forward mode or the reverse mode with respect to the A-side 2. However, if it is loaded in the apparatus with B-side 3 up, recording or reproducing is also executed on or from the predetermined track in the forward mode or the reverse mode with respect to the B-side 3. Thus, the forward-use track of the A-side 2 coincides with the reverse-use track of the B-side 3, while the reverse-use track of the A-side 2 coincides with the forward-use track of the B-side 3. Therefore, the user may become confused unless he or she takes notice of the side of the C-cassette 1 to be loaded in the apparatus. However, in most of the car-use tape recorders and portable tape recorders, it is difficult to confirm which side is on with respect to the cassette that has been loaded.
In order to solve the above problems, such systems have been developed; for example, Japanese Examined Patent Publication No. 3-55896 (55896/1991) discloses a system wherein judgement is made as to which side is up by providing a means for detecting a machine screw hole 6 or a machine screw 7 on the A-side 2 in the C-cassette 1 and the necessary operation is carried out based on the results of the judgement.
In the case of the D-cassette 15, generally, the tape recorder main body is provided with an appropriate function in order to avoid misloading. More specifically, if the D-cassette 15 is misloaded, the main body will not be able to find a recessed section for use in opening and closing of the slider at a predetermined position and thus the member for opening and closing the slider will not be able to make a proper action, thereby indicating a misloading.
Moreover, as to which cassette is loaded, C-cassette 1 or D-cassette 15, since the C-cassette 1 does not have a recessed section for use in opening and closing of the slider, which is provided in the D-cassette 15, the detection is made as to which kind of cassette is loaded by utilizing the difference of the travelling distance of the member for opening and closing the slider, or the detection is made by using switches or other devices by utilizing the difference of shapes between the C-cassette 1 and the D-cassette 15.
As described above, in a tape recorder that can handle the recording and reproducing functions thereon and therefrom of both the C-cassette 1 and the D-cassette 15, it is necessary to provide means to meet the following requirements:
(1) the ability to detect which cassette is loaded, C-cassette or D-cassette. PA1 (2) the ability to judge which side of the cassette facing up in the case of recording or reproducing information on or from the C-cassette 1 in the automatic reversing mode. PA1 (3) the ability to prevent misloading of the D-cassette 15 or to detect a misloaded D-cassette 15.
However, conventional cassette-detection devices for use in magnetic tape apparatuses, although they are provided with means for handling the above requirements individually, have not succeeded in satisfying all the requirements by the use of simple means.
More specifically, for example, it is extremely difficult to simultaneously satisfy the requirements (1) and (3) by utilizing the member for opening and closing the slider 18, and it is inevitable that a complicated structure is needed to satisfy all these requirements.
Further, if all the requirements (1), (2) and (3) are to be satisfied by providing proper electric circuits, switches or other devices that meet the respective requirements should be installed, resulting in the necessity of complicated wiring.